The more that software-defined networking (SDN) comes into focus, the more it appears that application delivery will play a major role.
Indeed, it already appears to some that SDN is simply the next evolutionary step in the drive to produce a dynamic network infrastructure that acts to support and propel application and data performance, rather than inhibit it.
A leading voice on the intersection of SDN and ADN is F5's Lori MacVittie, who notes that both initiatives are based on the notions of decoupled control and data planes, logically centralized intelligence and infrastructure abstraction. Moreover, the overriding goals of both include overcoming network protocol limitations and VLAN restrictions, reducing volatility in the IP network by adding greater operational consistency across network devices, and greater adaptability to business and operational needs through improved programmability and visibility. The main difference between the two is that they reside in different layers of the network stack, leading to the question: Will they operate in tandem, or will SDN ultimately supersede ADN?
Already, the jockeying for position has begun as virtualization, application management and advanced network fabric technologies converge on SDN. Citrix Systems, for example, just released the newest version of the NetScale SDX ADC platform that offers tools like AppTemplates that enable application-driven network control and embedded app intelligence, and AppFormations that uses packaged network services to improve deployment processes. At the same time, the company has teamed up with Palo Alto Networks in a bid to support a greater variety of data center network architectures through integrated deployments of XenApp and XenDesktop environments.
Meanwhile, Brocade has extended support for VMware's VXLAN SDN platform to the ADX application delivery controller in a bid to foster traffic interconnects between virtual and physical networks. A VXLAN gateway based on the ADX platform would enable broad scaling and security capabilities across Layer 3, multitenant virtual networks, allowing workloads to traverse a variety of network environments. It would also improve the enterprise's ability to load balance across disparate resources, both on a local and wide-area level.
Some people are even talking about a future beyond both ADN and SDN — something more akin to application-defined networking (ADN). Cloud networking specialist Lyatiss Inc. envisions an environment in which applications take an active role in provisioning and controlling the network resources needed to perform their required functions. In this world, the app would take control of networking APIs so as to optimize public and private cloud resources while maintaining both portability and security. To get there, the IT industry will have to grapple with some fundamental definitions surrounding the application environment, starting with the very notion of a "defined" network, and then moving on to the functions, capabilities and ownership of these customized functions.
It's way too early in the ADN/SDN development curve to start talking about end-game strategies, however. For the here and now, the movement seems to be about fostering better communications across application and network layers so that resources can be tailored to improve application performance and user-data coordination.
At the moment, ADN and SDN approach this goal through different means, but it isn't unreasonable to expect that these differences will fall away as development continues.